This invention generally relates to an absorbent article and an absorbent structure for such an article. The absorbent structure may include absorbent fibers and a reinforcing member. The reinforced absorbent structure can be employed in absorbent articles, such as disposable diapers, child's training pants, feminine care articles, incontinence articles, bandages, and the like.
Absorbent articles, such as for disposable absorbent garments, may include absorbent structures or cores conventionally formed by air forming or air laying techniques. For example, the manufacture of the absorbent core may begin by fiberizing a fibrous sheet of cellulosic or other suitable absorbent material in a conventional fiberizer, or other shredding or comminuting device, to form discrete fibers. In addition, particles of superabsorbent material are mixed with the discrete fibers. The fibers and superabsorbent particles are then entrained in an air stream and directed to a foraminous forming surface upon which the fibers and superabsorbent particles are deposited to form an absorbent fibrous web. In addition, bonding agents or other strengthening components may be incorporated to provide a more stabilized web.
Other techniques have also been employed to form webs of stabilized absorbent material. Such techniques have included dry-forming techniques, wet-laying techniques, foam-forming techniques, and various wet-forming techniques. The resulting webs of absorbent material have included absorbent fibers, natural fibers, synthetic fibers, superabsorbent materials, binders, and strengthening components in desired combinations. However formed, the absorbent web may then be stored or immediately directed for further processing (e.g., being cut into individual absorbent cores) and assembly with other components to produce a final absorbent article. Absorbent material webs have been strengthened by adding reinforcing members on at least one side of the absorbent material webs. Such reinforcing members have included reinforcement filaments, tissue layers, fabric layers and netting materials. It is also known to add staple binder fibers to the absorbent materials upon formation of the absorbent material web. The binder fibers are activated by heat to produce adhesion of the absorbent materials.
Integrity of an absorbent core formed from such an absorbent material web is desirable to avoid bunching, clumping, cracking and separating of the absorbent core in either a wet or a dry state. This improves the fit and comfort to the wearer of an absorbent article incorporating the absorbent core even as the article receives insults. Sagging and drooping of the absorbent article can cause gaps between the article and the wearer's body which may lead to leaking. As absorbent cores are made both thinner and narrower (particularly in the crotch region), stresses encountered in manufacture and use can be high, requiring reinforcement. In manufacture, tension on the absorbent core can be particularly high during start up and shut down of processing machinery. In use, the lack of integrity can make the absorbent article fit poorly and impact product performance by breaking up the absorbent core, and thereby inhibiting fluid control, liquid handling and wicking which can contribute to leaking.
Co-assigned European Patent Publication No. 0 467 409 A1 discloses one attempt to reinforce an absorbent pad using a scrim material. In that disclosure, a netting or scrim material is used in which some strands have an inner core of one material and an outer sheath of a second material. The scrim is introduced into a forming chamber in which it is incorporated into a fibrous matrix. The second material of the sheath has a lower melting point than the first material of the core. After incorporation of the scrim into the fibrous matrix, the absorbent web formed is heated to melt the sheath for bonding the scrim to the fibers in the matrix. This requires an extra step in the manufacture of a reinforced absorbent.
European Publication No. 0 467 409 also discloses a method for establishing the position of the scrim within the thickness of fibrous matrix. The method does not necessarily require the use of scrim of strands having inner cores and outer sheaths of different material. However, there is no disclosure or suggestion that securing the scrim to the fibrous matrix can be achieved without the use of adhesive and/or fusion bonding.
Conventional reinforcement materials, such as those described above, have exhibited significant shortcomings when employed to form desired absorbent structures. In order to connect the reinforcing member to the surrounding material adhesives and other forms of bonding have been employed which require additional or more complicated manufacturing techniques. Moreover, the conventional reinforcement materials have been expensive, and have had edges that can excessively irritate a wearer's skin. As a result, it has been difficult to provide an absorbent structure that has a desired combination of low-cost, high strength and low irritation. Accordingly, there has been a continued need for an improved technology for providing the desired, reinforced absorbents.